Supersonic flows over shallow cavities
(Sridhar, Gai, Kleine)
The study of compressible cavity flow has been an important topic in the field of aerodynamics and acoustics. Cavity flows are encountered in essentially all moving vehicles, from automobiles to aircraft to missiles. These cavities are present in the aircraft in the form of weapon bays, landing doors etc. Although the geometry of these cavities is simple, their unsteady fluid dynamic behaviour is complicated and difficult to predict both in subsonic and supersonic flows. These fluid phenomena typically cause unwanted drag, structural noise and vibrations.
The results show that the flow undergoes a significant structural change when L/D is increased beyond about 5. Cavities with L/D < 5 show a highly unsteady oscillatory structure while those with L/D > 5 exhibit a steady oscillatory flow within the cavity. This has important implications with regard to noise and vibrations of a structure that incorporates cavities in its design.
Two streamline plots for the case of L/D = 3: the flow field is characterised by the presence of a number of unsteady vortices.
